Rule of thumb for live axle pivot point

[srcjahc]

What is the golden rule for the pivot point for a live axle? I'm combining various rolling frames and am using the front end of a Kandi Spyder and a body of a Chinese UTV. I have a Dana transmission and torque converter mounted on a factory live axle from a Cub Cadet Big Country 4x2. Problem is the Cub Cadet live axle is LONG. Can I mount the pivot point under the seats? I want a short wheel base SxS and wonder what the handling would be like.

 

[panchothedog]

If you move the axle too far forward ( I think that's what you're asking ) with the engine hanging way out back you might have a hard time keeping any weight on the front wheels. Steering would be almost non existent.

 

[srcjahc]

Not just the axle but the entire swing arm. Its the hinge point where the swing arm attaches to the frame. How far forward (or back) should that hinge point be? No further than the middle of the frame? Behind the seats? Hoping to see if there is some sort of rule of thumb.

 

[Denny]

There is not any rules where you can put the hinge point. But common sense dictates you put it where it can move freely up and down. Usually after the seats.

 

[srcjahc]

I agree USUALLY after the seats, but was wondering how the ride hand handling might be affected if the hinge point was just forward of the seats. There's still room for the engine and transmission assembly to move up and down. The upper part of the shocks will be mounted to the frame behind the seats and the lower part of the shocks to the axle. Guess I'll just build it and see.

 

[bob58o]

I’m confused… if the hinge point of the swing arm is in front of the seats… why not just keep moving it forward until the hinge point of swing arm is the front axle?

What I’m getting at… is there a point where the hinge is so far forward that the swing arm no longer does what a swing arm should do.

If the seat is on the back part, it no longer separates the rider from the swing arm. Why even have it?

Am I not understanding the idea of suspension correctly?

It would be like putting the seat on the swing arm of a motorcycle??? Why???

Somebody please correct me if wrong, but it makes no sense to put the pivot in front of the seats.

 

[Master Hack]

​

I sense trouble brewing.
I'll throw in my worthless comment as I have nothing worthwhile to contribute.

​

rule of thumb​

noun phrase​

1
: a method of procedure based on experience and common sense

2
: a general principle regarded as roughly correct but not intended to be scientifically accurate

originally referred to people using the width of their thumb as a measuring tool, “rule” can refer to either a ruler/measuring stick or a guideline.

 

[bob58o]

I drew this picture to play Devils Advocate with myself. I guess the pivot point can be in front of the seat if the seat attaches in front of the pivot point.

 

[BaconBitRacing]

I don't see why not. Trophy trucks have them pretty far forward.

 

[bob58o]

I don't see why not. Trophy trucks have them pretty far forward.View attachment 149893

But you still want the seats attached in front of the pivot point, right?

 

[bob58o]

Or something like this? I need help visualizing what the idea is here.

 

[BaconBitRacing]

Or something like this? I need help visualizing what the idea is here.

View attachment 149895

I don't see the point in complicating the build by putting it further forward, but it's possible, I guess. I see no benefit putting in front of the seat.

 

[ezcome-ezgo]

Longer control arms are always better in my opinion, but you can't go nuts with it.

 

[Denny]

Until you start increasing unsprung weight. Then the suspension gets lazy.